🌱 Add util which is able to merge golang source code fragments based custom rules

go.mod

@@ -18,6 +18,7 @@ require (
 )
 
 require (
+	github.com/dave/dst v0.27.3 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-task/slim-sprig/v3 v3.0.0 // indirect

go.sum

@@ -1,5 +1,7 @@
 github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/dave/dst v0.27.3 h1:P1HPoMza3cMEquVf9kKy8yXsFirry4zEnWOdYPOoIzY=
+github.com/dave/dst v0.27.3/go.mod h1:jHh6EOibnHgcUW3WjKHisiooEkYwqpHLBSX1iOBhEyc=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=

pkg/plugin/util/merge/merge.go

@@ -0,0 +1,150 @@
+package merge
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"path"
+	"reflect"
+	"strconv"
+	"strings"
+
+	"github.com/dave/dst"
+	"github.com/dave/dst/decorator"
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+func InsertCode(filename, code string) error {
+	fset := token.NewFileSet()
+
+	sourceAst, err := parser.ParseFile(fset, filename, nil, parser.ParseComments)
+	if err != nil {
+		return err
+	}
+	mergingAst, err := parser.ParseFile(fset, "", code, parser.ParseComments)
+	if err != nil {
+		return err
+	}
+
+	for _, mImp := range mergingAst.Imports {
+		merging := true
+		for _, sImp := range sourceAst.Imports {
+			if importEqual(sImp, mImp) {
+				merging = false
+				break
+			}
+		}
+		if merging {
+			astutil.AddNamedImport(fset, sourceAst, defaultImportAlias(mImp), mustUnquoteImport(mImp))
+		}
+	}
+
+	sourceDst, err := decorator.DecorateFile(fset, sourceAst)
+	if err != nil {
+		return err
+	}
+	mergingDst, err := decorator.DecorateFile(fset, mergingAst)
+	if err != nil {
+		return err
+	}
+
+	for _, mDecl := range mergingDst.Decls {
+		merging := true
+		for _, sDecl := range sourceDst.Decls {
+			if declEqual(sDecl, mDecl) {
+				merging = false
+				break
+			}
+		}
+		if merging {
+			sourceDst.Decls = append(sourceDst.Decls, mDecl)
+		}
+	}
+
+	if err = decorator.Print(sourceDst); err != nil {
+		return err
+	}
+
+	// dst.Fprint(os.Stdout, sourceDst, dst.NotNilFilter)
+
+	return nil
+}
+
+func declEqual(src, trg dst.Decl) bool {
+	if reflect.TypeOf(src) != reflect.TypeOf(trg) {
+		return false
+	}
+	switch srcType := src.(type) {
+	case *dst.GenDecl:
+		trgType := trg.(*dst.GenDecl)
+		if srcType.Tok != trgType.Tok {
+			return false
+		}
+		switch srcType.Tok {
+		case token.IMPORT:
+			return true
+		case token.TYPE:
+			if skipSpecs(srcType.Specs, trgType.Specs) {
+				return false
+			}
+			return srcType.Specs[0].(*dst.TypeSpec).Name.Name == trgType.Specs[0].(*dst.TypeSpec).Name.Name
+		case token.VAR:
+			if skipSpecs(srcType.Specs, trgType.Specs) {
+				return false
+			}
+			srcVarName := srcType.Specs[0].(*dst.ValueSpec).Names[0].Name
+			tgtVarName := trgType.Specs[0].(*dst.ValueSpec).Names[0].Name
+			if srcVarName == "_" && tgtVarName == "_" {
+				srcVarType := srcType.Specs[0].(*dst.ValueSpec).Type.(*dst.SelectorExpr)
+				tgtVarType := trgType.Specs[0].(*dst.ValueSpec).Type.(*dst.SelectorExpr)
+
+				return srcVarType.Sel.Name == tgtVarType.Sel.Name
+			}
+
+			return srcVarName == tgtVarName
+		default:
+			return true
+		}
+	case *dst.FuncDecl:
+		if srcType.Name == nil || trg.(*dst.FuncDecl).Name == nil {
+			return false
+		}
+
+		return srcType.Name.Name == trg.(*dst.FuncDecl).Name.Name
+	}
+
+	return false
+}
+
+func skipSpecs(src, tgt []dst.Spec) bool {
+	return len(src) == 0 || len(tgt) == 0 || len(src) != len(tgt)
+}
+
+func importEqual(src, trg *ast.ImportSpec) bool {
+	return src.Path.Value == trg.Path.Value && importAlias(src) == importAlias(trg)
+}
+
+func defaultImportAlias(spec *ast.ImportSpec) string {
+	if spec.Name == nil {
+		return ""
+	}
+
+	return spec.Name.Name
+}
+
+func importAlias(spec *ast.ImportSpec) string {
+	if spec.Name == nil && spec.Path != nil {
+		return strings.ReplaceAll(path.Base(mustUnquoteImport(spec)), "-", "")
+	}
+
+	return spec.Name.Name
+}
+
+func mustUnquoteImport(importSpec *ast.ImportSpec) string {
+	res, err := strconv.Unquote(importSpec.Path.Value)
+	if err != nil {
+		panic(err)
+	}
+
+	return res
+}

pkg/plugin/util/merge/merge_test.go

@@ -0,0 +1,31 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package merge
+
+import (
+	_ "embed"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+//go:embed testdata/merge.go.file
+var mergeCode string
+
+var _ = Describe("MergeUtil", func() {
+	It("returns an error if the command fails", func() {
+		err := InsertCode("./testdata/source.go.file", mergeCode)
+		Expect(err).To(Succeed())
+	})
+})

pkg/plugin/util/merge/suite_test.go

@@ -0,0 +1,29 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package merge
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestStage(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Merge Utils Suite")
+}

pkg/plugin/util/merge/testdata/merge.go.file

@@ -0,0 +1,126 @@
+/*
+Copyright 2025.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1beta1
+
+import (
+	"context"
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	ctrl "sigs.k8s.io/controller-runtime"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/webhook"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+
+	batchv1beta1 "my.domain/guestbook/api/v1beta1"
+)
+
+// nolint:unused
+// log is for logging in this package.
+var cronjoblog = logf.Log.WithName("cronjob-resource")
+
+// SetupCronJobWebhookWithManager registers the webhook for CronJob in the manager.
+func SetupCronJobWebhookWithManager(mgr ctrl.Manager) error {
+	return ctrl.NewWebhookManagedBy(mgr).For(&batchv1beta1.CronJob{}).
+		WithValidator(&CronJobCustomValidator{}).
+		WithDefaulter(&CronJobCustomDefaulter{}).
+		Complete()
+}
+
+// TODO(user): EDIT THIS FILE!  THIS IS SCAFFOLDING FOR YOU TO OWN!
+
+// +kubebuilder:webhook:path=/mutate-batch-my-domain-v1beta1-cronjob,mutating=true,failurePolicy=fail,sideEffects=None,groups=batch.my.domain,resources=cronjobs,verbs=create;update,versions=v1beta1,name=mcronjob-v1beta1.kb.io,admissionReviewVersions=v1
+
+// CronJobCustomDefaulter struct is responsible for setting default values on the custom resource of the
+// Kind CronJob when those are created or updated.
+//
+// NOTE: The +kubebuilder:object:generate=false marker prevents controller-gen from generating DeepCopy methods,
+// as it is used only for temporary operations and does not need to be deeply copied.
+type CronJobCustomDefaulter struct {
+	// TODO(user): Add more fields as needed for defaulting
+}
+
+var _ webhook.CustomDefaulter = &CronJobCustomDefaulter{}
+
+// Default implements webhook.CustomDefaulter so a webhook will be registered for the Kind CronJob.
+func (d *CronJobCustomDefaulter) Default(ctx context.Context, obj runtime.Object) error {
+	cronjob, ok := obj.(*batchv1beta1.CronJob)
+
+	if !ok {
+		return fmt.Errorf("expected an CronJob object but got %T", obj)
+	}
+	cronjoblog.Info("Defaulting for CronJob", "name", cronjob.GetName())
+
+	// TODO(user): fill in your defaulting logic.
+
+	return nil
+}
+
+// TODO(user): change verbs to "verbs=create;update;delete" if you want to enable deletion validation.
+// NOTE: The 'path' attribute must follow a specific pattern and should not be modified directly here.
+// Modifying the path for an invalid path can cause API server errors; failing to locate the webhook.
+// +kubebuilder:webhook:path=/validate-batch-my-domain-v1beta1-cronjob,mutating=false,failurePolicy=fail,sideEffects=None,groups=batch.my.domain,resources=cronjobs,verbs=create;update,versions=v1beta1,name=vcronjob-v1beta1.kb.io,admissionReviewVersions=v1
+
+// CronJobCustomValidator struct is responsible for validating the CronJob resource
+// when it is created, updated, or deleted.
+//
+// NOTE: The +kubebuilder:object:generate=false marker prevents controller-gen from generating DeepCopy methods,
+// as this struct is used only for temporary operations and does not need to be deeply copied.
+type CronJobCustomValidator struct {
+	// TODO(user): Add more fields as needed for validation
+}
+
+var _ webhook.CustomValidator = &CronJobCustomValidator{}
+
+// ValidateCreate implements webhook.CustomValidator so a webhook will be registered for the type CronJob.
+func (v *CronJobCustomValidator) ValidateCreate(ctx context.Context, obj runtime.Object) (admission.Warnings, error) {
+	cronjob, ok := obj.(*batchv1beta1.CronJob)
+	if !ok {
+		return nil, fmt.Errorf("expected a CronJob object but got %T", obj)
+	}
+	cronjoblog.Info("Validation for CronJob upon creation", "name", cronjob.GetName())
+
+	// TODO(user): fill in your validation logic upon object creation.
+
+	return nil, nil
+}
+
+// ValidateUpdate implements webhook.CustomValidator so a webhook will be registered for the type CronJob.
+func (v *CronJobCustomValidator) ValidateUpdate(ctx context.Context, oldObj, newObj runtime.Object) (admission.Warnings, error) {
+	cronjob, ok := newObj.(*batchv1beta1.CronJob)
+	if !ok {
+		return nil, fmt.Errorf("expected a CronJob object for the newObj but got %T", newObj)
+	}
+	cronjoblog.Info("Validation for CronJob upon update", "name", cronjob.GetName())
+
+	// TODO(user): fill in your validation logic upon object update.
+
+	return nil, nil
+}
+
+// ValidateDelete implements webhook.CustomValidator so a webhook will be registered for the type CronJob.
+func (v *CronJobCustomValidator) ValidateDelete(ctx context.Context, obj runtime.Object) (admission.Warnings, error) {
+	cronjob, ok := obj.(*batchv1beta1.CronJob)
+	if !ok {
+		return nil, fmt.Errorf("expected a CronJob object but got %T", obj)
+	}
+	cronjoblog.Info("Validation for CronJob upon deletion", "name", cronjob.GetName())
+
+	// TODO(user): fill in your validation logic upon object deletion.
+
+	return nil, nil
+}